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UNITED STATES HERMAN Ennsen, or

PATENT OFFICE.

CLEVELAND, ASSIGNOR vOF OXE-IIALF TOJOIIWV. VAN DYKE, Ol!` LIMA, OHIO. y

INCREASING THE FLow oF OIL-WELLS.

SPECIFICATION forming part of Letters Patent No. 556,669, dated March 17, 1896. Application iledJune 27, 1895. Serial No. 554,177. (No model.)

To all when?, it r11/ay concern.-

l3e it known that I, HERMAN FRASCH, a citi- .zen of the United States, residing at Cleveland, in the county of Cuyahoga and State of o Ohio, have invented a certain new and useful- Improvement in Increasing the Flow of OillVells; and I do declare the following to be a full, clear, and exact description of the invention. A

This invention relates to a method of increasiinr the iiow of oil-wells in limestone formations-such,for example,as the oil-wells of the Lima district in Ohio and Aof certain other parts of. the. United States and of Canada. lleretofore it has been customary to increase the fiow in these, as in other wells,"

by exploding torpedoes'therein. The effect of the explosion is to shatter the roek;.but

this is filled with liquid and the disintegra-l tion does not extend far.

The present invention consists Ain a new and superior method based upon chemical action.'

In accordance with the new method a chemical reagent which attacks the limestone-rock,

'in which the well is, is introduced thereinto' at a distance' from the 'original well-hole. As

these wells are ordinarily of great depthsay twelve hundred feet-an enormous pressure may thus be developed, and, if desired, other pressure-producing means may be employed.

It is` an' advantage to confine the reagent outside the supply-pipe to thelower or oil-yielding portion' of the well-hole. This can be done by asuitably-arranged packer which shuts oi the lower from the upper portion of the hole and prevents the reagent from ascendin g above the packer. The reagent seems to act chiefly upon the films which bind together the more solid particles, and thus by disintegrating the rock into a more or less sand-like mass to increase its porosity.' A s a rcsultvof` this action a larger territory maT be drained, while the oil hasa larger surface through which to filter and a more readyv access to the well-hole. l-y using enough acid and pressing it back into the rock long channels can be formed and oil reached thereby which otherwise could not be had without drilling other wells, if at all. der that the product of the chemical reaction may not remain in the roch to obstruct the passages and to diminish the well-cavity use is made of a reagent, such as hydrochloric or muriatic acid, which in attacking dissolves the rock, or, in other words, forms a soluble compoun'd of calcium, such as the chloride, for example. The use of commercial muriatic or lrvdrochloric acid (which is of a specific gravity from 1.15 to .1.20 and contains from thirty to forty per cent. by weight of the acid gas HCI) is recommended, from about one thousandto two 'thousand gallons of such commercial acid being p preferably employed for a dose.

The enlargement of the well-cavity is in itself of importance, particularly with small wells,'for the wells cease to ow when they become full, and with small wells it is thereln orfore necessary to pump out at short intervals,

which is more expensive than to remove the same quantity of oil by less frequent pumpings.

After introducing a suitable quantity of the cause it to penetrate farther into the rock by forcing a neutral or cheap liquid, such as water, into the well, and it is also advantageous hole and may be done with the usual sandpump, the usual drilling-tools being used (if necessary) to loosen any hard sediment which may form. More or less of the liquid which returns to the well-hole would be removed reagent it is advantageous to displace it andv IOO lits action.

with the said solid particles; but that which is free from the finely-divided solid matter or sand-like particles can be removed by the pumping apparatus (composed of tubing and sucker-rod) which is employed to pump the oil. liy theuse of a chemical reagentwhich forms a soluble salt of calcium the productsl of the chemical decomposition of -the lime- `stone are removed with the liquid in which the salt of calcium is dissolved, and which conveys the same from the remotest points. 'lhe channels which have been cut in the rock are thus left free, thereby securing the maximum increase of the iiow of oil as well as of the oil-holding .capacity of the well.

'llic following is a description of what is considered the best mode of carrying out the invention, reference being had to the accompanying drawings, which form part of this specification, and in which- Figure I is a diagram of a Well with the supply or reagent-introducing pipe in place, and Fig. Il is a detail view illustrating a mode of protecting the said pipe.

The pipe,A is provided with a rubber packer l5 in the rock above the Trenton limestone O, in which the well is. It may bc enameled or lead-lined pipe, externallycoated withA enamel or lead below the packer B, or it may be otherwise made proof against corrosion. There is a box D provided with a funnelshaped bottom to feed the acid to the pipe A. As shown in Fig. 1I the pipe A is lined wit-l1 a tube 2 of soft rubber and covered exteriorly with anothersoft-rubber tube 3, the lower end of the inner tube being turned back over the pipe A, and also over the outer tube, and the whole wrapped to prevent ingress of liquid at the joint.

The reagent (muri atie or hydrochloric acid) is placed in the box 1),'which is kept l ull, so that the pressure of the whole column (of twelve hundred feet, if that be the depth of the well) is exerted upon the acid in the well, which acid is by the pressure and its own corrosive action forced into the rock, greatly increasing its porosity and extending the area drained by the well and also enlarging the well-cavity. lVhen as much acid as desired, say one thousand gallons, has gone into the rock, a force-pump is connected with the pipe A'and fresh water is forced down to displace the acid in the pipe and rock, and by forcing it still farther int-o the rock extend the area of After a rest of, say, twelve hours milk of lime is pumped down to neutralize any trace of acid that might exist. '.lhe well is then cleaned out and the tubing replaced,

and the work of pumping oil carried on as usual. Y

The usual sand-pump may be used in cleaning out, and it may, of course, 'be employed as often as necessar f, after `pumping is resumed, in order to remove solid particles which may be brought -into the wcll-holeduring the pumping, the tubing being temporarily removed in order Ato allow the use of the sand-pump.

Other reagents may be used instead of hydrochloric or muriatic acid, although this is preferred byreason of its effi ciencv and cheapness. 4

'lhe rock might also be acted upon with the aid of a gaseous reagent, instead of simply by a liquid---as, i'or exam ple, the rock might be decomposed by introducing hydrochloric-acid gas into the Well and the resulting chlorideoi'l calcium be dissolved in water artiii cially vintroduced or natura-ll)r present in the well.

l claim as my invention or discovery-, v

ing such reagent in the well `to strong press'- ure; substantially as described.

2l. The method of increasing the ilow of oilwells in limestone formations, by introducing into the well a large quantity' of a chemical reagent which is a solvent of the rock (such as hydrochloric or muriatic acid), and allow ing said reagent to act upon the walls of `the .wellg substantially as described.

4. The method of increasing'the flow of oilwells in limestone formations, by introducing into the well a large quantity of a chemical. reagent which is a solvent of the rock (such as hydrochloric or muriatie acid), and subjecting such reagent to strong pressure; substantially as described.

5. The method of increasing the flow of oil- Wells in limestone formations, by introducing into the well a large quantity of a chemical reagent which attacks the rock, and allowing said reagent to actupon the walls of the well, and also introducing'a neutral or cheap liq- Auid such as water into the well to force the as hydrochloric or muriatic acid), and allowing said reagent to act upon the walls of the well, and also introducing a neutral or cheap liquid such as water into the'well to force the said chemical reagent farther into the rock;

substantially as described.

7. The method of increasing the ilow of oilwells in limestone formations, by introducing into the well rst a chemical reagent to a1.- tack the rockforming the walls, then 'a neutral o1'. cheap liquid such as water to force the reagent into the rock andsiinally a `neutralizinsr lifuid: substantially as described.

IOO

S. The method of increasing the flow of oilwells in limestone formations, by introdncimr int-o the Well a large quantity of a chemica reagent which attacks the rock, confining said reagent to the lower or oil-yielding portion of the Well-hole, and forcing it by pressure into thc rock; substantially as described.

9. The method of increasing the flow 0f oill Wells in limestone formations, by introducing into the well a large quantity of a chemical reagent which attacks the rock, forcing it by pressure into the. rock, removing the pressure, and cleaning ont the solid particles which in presence of twowitnesses. l v

HERMAN FRASCIL \\'itnesscs:

F. W. LOTHMAN, N. J, XVORLEY. 

